磷酸泛酰巯基乙胺基转移酶基因过量表达对集胞藻PCC6803脂肪酸合成的影响

Effects of over expression of phosphopantetheinyl transferases gene on fatty acid synthesis in Synechocystis sp.PCC6803

磷酸泛酰巯基乙胺基转移酶(phosphopantetheinyl transferases,PPTase)是细菌脂肪酸合成中的关键酶。本研究利用同源重组手段构建集胞藻PCC6803 PPTase基因(slr0495)过量表达重组质粒,在集胞藻PCC6803中进行表达研究,并在DNA和RNA水平进行验证,同时利用气相色谱-质谱联用仪(GC-MS)检测不同条件下突变藻株脂肪酸组分及含量。结果表明:在温度为30℃、光照强度为50μmol·m^(-2)·s^(-1)的培养条件下,过量表达slr0495基因突变藻株中C12:0、C16:0和C18:0的含量分别为1.31 mg·g^(-1)、8.07 mg·g^(-1)和1.35 mg·g^(-1),比野生型藻株分别提高了23.58%、25.31%和13.45%;在温度为20℃、光照强度为50μmol·m^(-2)·s^(-1)、50%NaNO_(3)的培养条件下,与野生型相比,突变藻株中C16:0和C18:0含量分别提高了44.71%和41.51%。以上结果表明,过量表达slr0495基因增加了集胞藻PCC6803中长链饱和脂肪酸的含量,并且在低温(20℃)和缺氮(50%NaNO_(3))双重胁迫培养条件下中长链饱和脂肪酸含量得到进一步提高。本研究为探究slr0495基因功能以及在逆境中基因产生的应激反应提供了理论依据,为微藻高产多不饱和脂肪酸代谢研究奠定了基础。

Phosphopantothenyl transferase(PPTase)is a key enzyme in fatty acid synthesis in bacteria.In this study,the homologous recombinant plasmid slr0495^((+)) was successfully constructed for overexpressing the PPTase(slr0495)gene and transformed into wild-type Synechocystis sp.PCC6803.The results showed that under the culture conditions of 30℃,50μmol·m^(-2)·s^(-1),the contents of C12:0,C16:0 and C18:0 in wild type Synechocystis sp.were 1.31 mg·g^(-1),8.07 mg·g^(-1),1.35 mg·g^(-1),while the C12:0,C16:0and C18:0 contents of mutant strains were 23.58%,25.31%and 13.45%higher than those of wild type strains,respectively.Under the culture conditions of 20℃,50%NaNO_(3) and 50μmol·m^(-2)·s^(-1) light intensity,compared with the wild type,the contents of C16:0 and C18:0 in mutant strains overexpressing slr0495 gene increased by 44.71%and 41.51%,respectively.These above results indicated that overexpression of slr0495 gene increased the contents of saturated long-chain fatty acids in Synechocystis sp.PCC6803,and the contents of medium-long-chain saturated fatty acids were further improved under the conditions of low temperature(20℃)and nitrogen deficiency(50%NaNO_(3)).This study not only provides a theoretical basis for further exploring the function of slr0495 and the stress response of this gene in adversity but also lays the foundation for further exploring the high-yield polyunsaturated fatty acids of microalgae.